Viscoelastic behavior of an ordering latex suspension in a steady shear flow

The linear viscoelastic behavior of an ordering polystyrene latex during steady shear flow has been investigated. In this study a home-made instrument has been used that superimposes a small-amplitude oscillatory shear orthogonal onto the steady shear flow. The measurements can be interpreted as due to the coexistence of two phases under flow. For increasing shear rate the ordered (or solidlike) phase melts away until the suspension becomes completely disordered (or fluidlike). A model is presented in which the fluid is conceived as a viscoelastic matrix containing spherical viscoelastic domains. The model predicts a similar linear viscoelastic behavior of sheared lattices as found experimentally. The resulting parameters give information about the microstructure of the dispersion under shear flow.